Meju is a fermented food that serves as the basis of traditional Korean fermented soybean foods, such as ganjang (soy sauce), gochujang (chili paste), and doenjang (soybean paste). Meju, made from soybeans as a principal ingredient, is also a starter of great importance for the preparation of traditional Korean condiments, that is, ganjang (soy sauce), gochujang (red chili paste), and doenjang (soybean paste).
Meju (fermented soybean) is largely classified into traditional meju, modified meju, or industrial koji (Kokja) depending on the preparation method. The traditional meju is made from, soybeans alone that are shaped, wrapped with rice straws, and then fermented for a defined period of time. The modified meju is prepared from soybeans steamed and fermented with a strain of Aspergillus sp. The industrial koji is produced by fermentation of wheat grains or wheat flour with Aspergillus oryzae. 
Gochujang (red chili paste) is largely classified into traditional (Korean style) gochujang and factory-made (modified) gochujang according to the preparation method. The traditional gochujang is a fermented condiment made from meju powder for gochujang (a mixture of soybean and grains at a given ratio), a starchy ingredient like glutinous rice, yeotgireum (barley malt powder), salt, and chili powder, through fermentation and aging. The factory-made gochujang is an aged diastatic gochujang using a koji with cultured Aspergillus oryzae; in place of meju powder for gochujang. In the production of koji, the protein ingredient is soybean; and the starchy ingredient is rice or wheat flour.
As more women enter the workforce outside the home, more people purchase factory-made gochujang. Hence, the production of factory-made gochujang is increasing, and the gochujang export is also on the rise.
As a conventional method to produce factory-made gochujang, KR Patent No. 10-0668056 discloses a soybean meju and its preparation method, where cultured microorganisms are inoculated into soybeans to ferment the soybeans. More specifically, the prior art describes a preparation method for soybean meju and a soybean meju prepared by the method, which method includes a steaming step of steaming and drying soybeans, and a fermentation step of inoculating cultured microorganisms isolated from traditional meju into the soybeans and then fermenting the soybeans for a defined period of time.
Even using the conventional method, there is still a demand for development of a soybean koji for large-quantity production of factory-made gochujang.